parse a special xml in python

Question

I have s special xml file like below:

<alarm-dictionary source="DDD" type="ProxyComponent">

    <alarm code="402" severity="Alarm" name="DDM_Alarm_402">
    <message>Database memory usage low threshold crossed</message>
    <description>dnKinds = database
    type = quality_of_service
    perceived_severity = minor
    probable_cause = thresholdCrossed
    additional_text = Database memory usage low threshold crossed
    </description>
    </alarm>

        ...
</alarm-dictionary>

I know in python, I can get the "alarm code", "severity" in tag alarm by:

for alarm_tag in dom.getElementsByTagName('alarm'):
    if alarm_tag.hasAttribute('code'):
        alarmcode = str(alarm_tag.getAttribute('code'))

And I can get the text in tag message like below:

for messages_tag in dom.getElementsByTagName('message'):
    messages = ""
    for message_tag in messages_tag.childNodes:
        if message_tag.nodeType in (message_tag.TEXT_NODE, message_tag.CDATA_SECTION_NODE):
            messages += message_tag.data

But I also want to get the value like dnkind(database), type(quality_of_service), perceived_severity(thresholdCrossed) and probable_cause(Database memory usage low threshold crossed ) in tag description.

That is, I also want to parse the content in the tag in xml.

Could anyone help me with this? Thanks a lot!

dbr · Accepted Answer · 2012-11-09 10:59:12Z

Once you have the text from the description tag, it's nothing to do with XML parsing. You just need do simple string-parsing to get the type = quality_of_service keys/values strings into something nicer to use in Python like a dictionary

With some slightly simpler parsing thanks to ElementTree, it would look like this

messages = """
<alarm-dictionary source="DDD" type="ProxyComponent">

    <alarm code="402" severity="Alarm" name="DDM_Alarm_402">
    <message>Database memory usage low threshold crossed</message>
    <description>dnKinds = database
    type = quality_of_service
    perceived_severity = minor
    probable_cause = thresholdCrossed
    additional_text = Database memory usage low threshold crossed
    </description>
    </alarm>

        ...
</alarm-dictionary>
"""

import xml.etree.ElementTree as ET

# Parse XML
tree = ET.fromstring(messages)

for alarm in tree.getchildren():
    # Get code and severity
    print alarm.get("code")
    print alarm.get("severity")

    # Grab description text
    descr = alarm.find("description").text

    # Parse "thing=other" into dict like {'thing': 'other'}
    info = {}
    for dl in descr.splitlines():
        if len(dl.strip()) > 0:
            key, _, value = dl.partition("=")
            info[key.strip()] = value.strip()
    print info

Idiot211 · Accepted Answer · 2012-11-09 10:53:22Z

2

I'm not completely sure on Python, but after quick research.

Seeing as you can already get all of the content from the description tag in XML, can you not split by line breaks, and then split each line using the str.split() function on the equals signs to give you name / value separately?

e.g.

for messages_tag in dom.getElementsByTagName('message'):
messages = ""
for message_tag in messages_tag.childNodes:
    if message_tag.nodeType in (message_tag.TEXT_NODE, message_tag.CDATA_SECTION_NODE):
        messages += message_tag.data
tag =  str.split('=');
tagName = tag[0]
tagValue = tag[1]

(I haven't taken into account splitting each line up and looping)

But that should get you on the right track :)

answered Nov 9, 2012 at 10:53

Idiot211

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4 Comments

dbr Over a year ago

Not valid Python, but that's definitely the way to solve the problem - unless the description was something like <info key="dnKinds">database</info>, it's not an XML problem

Idiot211 Over a year ago

Hehe, I had a feeling it wasn't but Python isn't my speciality (Haven't used it in a few years) so I just quickly perused the Python docs to provide an answer with some sort of good logic at least.

zhaojing Over a year ago

@ldiot211, Thanks a lot! yes, I think your solution definitely solve the problem!

Idiot211 Over a year ago

Glad to have been able to help sir!

Ofir Farchy · Accepted Answer · 2012-11-09 10:58:56Z

2

AFAIK there is no library to handle the text as DOM elements.

You can however (after you have the message in the message variable) do:

description = {}
messageParts = message.split("\n")
for part in messageParts:
    descInfo = part.split("=")
    description[descInfo[0].strip()] = descInfo[1].strip()

then you'll have inside description the information you need in the form of a key-value map.

You should also add error handling on my code...

answered Nov 9, 2012 at 10:58

Ofir Farchy

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